The present invention relates to an indicator-nut threaded coupling with load-indicating device, adapted to be arranged on anchors, in particular grouted anchors for mining or the like, it consisting of at least one free space lying on an outer wall surface, which space is narrowed and possibly closed when a certain limit load is exceeded.
Such an indicator nut threaded coupling with load-indicating device is available on the market, a bipartite hex nut being screwed on an anchor instead of a normal anchoring nut. This hex nut consists of an anchoring nut developed as load-bearing part and a test part facing the abutment. On the outer wall of the indicator nut there are slits which narrow and possibly close when a given limit load is exceeded, the nut ribs of the test part shearing off. As soon as the slit is closed, the anchoring force increases again rapidly up to the breaking load of the anchor. The slide path for the anchor which is freed by the yielding indicator nut is relatively small and frequently not sufficient for movements of strata or the like.